This may be a stupid CPAP question but I am so curious...

[boxofrain]

Hello everyone. I am quite sure some of you can give me a good answer to this question! Occasionally I find myself using the CPAP, maybe for a nap or something, but for some reason I end up not sleeping. Either I read or I just lay there daydreaming or something. Then when I check my stats, my AHI is MUCH higher than it would have been than if I had actually been sleeping. But when I lay there awake I never notice any time at all that my airway is compromised or I stop breathing or gasp. Nothing! I heard Pugsy say several times when you are not sleeping there may be false readings (not an exact quote). My question is why? What is going on with AHI and episodes when we are actually awake with the CPAP on? Thanks!

[Pugsy]

These machines measure air flow only. They have zero way to know if we are asleep or not.

Asleep breathing is very rhythmic and stable and predictable.
Awake breathing is very erratic at times when compared to asleep breathing. The machine will flag the erratic air flow because all it measures is air flow. The flagged awake breathing episodes are commonly referred to here as sleep/wake/junk or SWJ for short.
The machine still counts them though but they don't really matter since were weren't asleep. You have to be asleep for them to really matter. It's called sleep apnea for a reason and not awake apnea.

Below is an example I use often to show asleep breathing and awake/arousal breathing and all the flagged events are false positive flags or SWJ. The asleep breathing is circled in red. All that stuff after that is awake/arousal related and simply doesn't count in terms of therapy evaluation.

If you want to learn more about asleep breathing vs awake breathing you can watch the videos here
http://freecpapadvice.com/sleepyhead-free-software
Bear in mind while they talk mainly about central apneas / Clear Airway apneas....any event category can end up flagged as a false positive. I see all categories flagged while I am obviously awake.

[boxofrain]

Thank you so much for the explanation Pugsy!


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[chunkyfrog]

There are no stupid questions . . . I think.

[boxofrain]

Thanks Chunky!


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[palerider]

Hello everyone. I am quite sure some of you can give me a good answer to this question! Occasionally I find myself using the CPAP, maybe for a nap or something, but for some reason I end up not sleeping. Either I read or I just lay there daydreaming or something. Then when I check my stats, my AHI is MUCH higher than it would have been than if I had actually been sleeping. But when I lay there awake I never notice any time at all that my airway is compromised or I stop breathing or gasp. Nothing! I heard Pugsy say several times when you are not sleeping there may be false readings (not an exact quote). My question is why? What is going on with AHI and episodes when we are actually awake with the CPAP on? Thanks!

Without an EEG on your head, you don't know whether you slept or not.

The brain doesn't form memories during sleep, which is the same reason people don't remember waking up as many as hundreds of times a night with untreated sleep apnea, and most people don't remember waking up during sleep cycles.

Sometimes I'll put on the mask and think I didn't drift off while laying there, and I don't remember drifting off, but I'll feel the restorative feelings of having had a nap.

Also, awake breathing tends to be very irregular.

[palerider]

There are no stupid questions . . . I think.

Oh yes, there are a LOT of stupid questions out there, they're often asked on this forum.
Questions where someone didn't bother to read the pinned announcements that have the answers, questions about things that are actually quite simple, had the person stopped to try and reason out the answer for more than a 10th of a second, etc.

However, the OPs question wasn't one of the stupid ones.

[chunkyfrog]

There are no stupid questions . . . I think.

Oh yes, there are a LOT of stupid questions out there, they're often asked on this forum.
Questions where someone didn't bother to read the pinned announcements that have the answers, questions about things that are actually quite simple, had the person stopped to try and reason out the answer for more than a 10th of a second, etc.

However, the OPs question wasn't one of the stupid ones.

Sadly, there are many examples--on and offline.
It doesn't take a genius to look, read, and think; but I occasionally get confused for one.
Most people likely have enough smarts, but they don't want to use them.
I blame parents, who praise their kids for beauty and athleticism, but no points for cleverness.